Stock markets dropped on Trump's bellicose Truth Social post that said China is "becoming very hostile" in seeking tough export controls on rare earths.

China has leveraged its control of the sector in trade talks with the U.S. by threatening a disruptive global shortage of the critically-needed minerals.

After tightening restrictions during the tariff tit-for-tat in April, China has further amped up controls on the minerals, which are essential for the tech and auto industries.…